1. Field of the Invention
The present invention relates to an imaging system, particularly, to an imaging system performing communication between an interchangeable lens and an imaging apparatus, an imaging apparatus, an interchangeable lens, a method of controlling these, and a program for causing a computer to perform the method.
2. Description of the Related Art
In recent years, imaging apparatuses, such as a digital still camera, a digital video camera (for example, a camcorder), etc., have become widespread. The imaging apparatuses capture an image of a subject, such as a person, an animal, etc., generate image data, and record the image data as an image content. Also, imaging apparatuses capable of attaching various kinds of interchangeable lenses have become widespread. For example, a lens unit (interchangeable lens) including a zoom lens, a focus lens, etc., is allowed to be attached to and detached from the imaging apparatuses.
For example, when image-capture operation is performed using an imaging apparatus with an interchangeable lens attached (an imaging system including an interchangeable lens and an imaging apparatus), the imaging apparatus performs various kinds of operation processing, such as exposure, focusing, white balance, etc. In this manner, when the imaging apparatus performs various kinds of operation processing, the imaging apparatus uses image data generated by imaging processing and state information of each member, such as a position of each lens in the interchangeable lens, an aperture value (F number) of an aperture, etc. Accordingly, when image-capture operation is performed using an imaging apparatus to which an interchangeable lens is attached, it is necessary to perform communication between the interchangeable lens and the imaging apparatus. That is to say, the imaging apparatus obtains state information of each member in the interchangeable lens, and performs various kinds of operation processing using the obtained state information. And the imaging apparatus makes a drive request for driving each member in the interchangeable lens on the basis of these individual operation results to the interchangeable lens.
For example, a proposal has been made on an actuator control apparatus in which state information of an actuator is fetched on a predetermined control cycle, control parameters of the actuator are obtained on the basis of the information, and the control parameters are output on a predetermined control cycle (for example, refer to Japanese Unexamined Patent Application Publication No. 2000-56379 (FIG. 1).